Thyroid UK
82,641 members97,668 posts

Suppressed TSH from Pituitary

Hello friends ...

Just came back from my doctor visit, my T4 17.6 (Normal 10-28) and TSH 0.038 (Normal 0.46-4.68). I'm on 100 mcg Levothyroxine since more than 5 months now. I believe my doctor that my T4 is fine at this level, I tried to take 150 mcg to rise T4 to 21 but I didn't get any benefits. He believes I have a pituitary issue! MRI didn't show anything wrong with it neither ACTCH challenge test show anything wrong with cortisol or ACTCH. I'm getting 50% improvement with Levothroxine but still wake up at 4 am and feel exhausted short of breath. I might look for another doctor for more tests!!

10 Replies

An FT4 of 17 in a range that goes up to 28 isn't exactly stellar - I'm not sure I'd agree that it's fine. The suppressed TSH happens in many of us who take thyroid hormone replacement therapy. It might be that the reason 150mcg of Levo made no difference is because it still wasn't enough for you - again, 21 in a range that goes to 28 still isn't great. The test you really need is FT3 - no amount of staring at FT4 results and TSH will tell your doctor whether your body is capable of making enough T3 out of the Levo you're taking.

Another doctor might be amenable to testing FT3 - but possibly not - in which case you could pursue getting that test done privately.

So sorry you're struggling to get decent treatment. Have you had ferritin checked or Vit B12? The breathlessness might be to do with anaemia (although breathlessness can be a symptom of undertreated hypothyroidism).


Thanks for the quick replay. So sorry, I meant my T4 went to 24.2 (10-28) when I took 150 mcg for a month based on an advise from here that T4 should be in the top range. Since I didn't get the benefits I was looking for, I drooped back to 100 mcg.

Yes, the doctor doesn't want to test T3 nor RT3! I don't agree with him! but from last several blood works, T3 seems to rise with T4.

- Ferritin (239 Normal is 20-300) and Iron 61 (49-181) both look normal.

- Vit D and B 12 both normal, I supplemented both to go to higher ranges.


T3 does not always rise with the T4. It depends if you are converting well. Your Ferritin is high - which can indicate some sort of inflammation in the body. Once you are supplementing B12 the tests are meaningless - just assume you will always need it when Hypo.

T3 is the most active thyroid hormone and needed in every cell of the body - so VERY important to know that reading....


Hi, your levels and ranges. Your suppressed TSH Isn't really much to,worry about at the min, your FT4 should be about 55-60% of the range, and your FT3 should be around 75-80% of the range, this is where most people feel at their best level wise so as an idea you could split the difference and increase your levothyroxine to 125mcg tell your doctor you need to know your FT3 levels to see if your converting correctly. Otherwise you could have an ok FT4 and if your not converting properly, you then gave another issue going in like iron, adrenals etc. Why does he think you have a pituitary issue? I ask because if he won't test your FT3 I'm guessing he's not tested your other hormones, like sex hormones, DHEA etc, or have you had a head injury in the past? Pituitary issues usually have other hormone problems too as just mentioned... Hope that helps and not confused you..?


Good question, I'm coming back to this post to add more info about this. He thinks pituitary is not producing enough TSH, because it was suppressed before I take levothyroxine while my T3/T4 are in normal mid-ranges. He did T3 initially and it looked to respond well to the increase of T4.

He didn't do sex hormones, DHEA etc , I will ask him next visit.


Yes I totally agree. Testing FT3 and adrenal function is v important. I have had mine done privately and now take pregnenolone which really helps for a v low adrenal gland. Previously I was v tired.

All I have to fix is how to get T3 privately as my practice no longer gives it anyone.


I also forgot to mention that TSH was suppressed even before start taking levo.


He believes I have a pituitary issue! MRI didn't show anything wrong with it neither ACTCH challenge test show anything wrong with cortisol or ACTCH.

Did anyone look at your hypothalamus? Have you ever had a test for TRH levels? It was apparently used in years gone by, and can still be done in rare cases..

TRH = Thyrotropin Releasing Hormone ; Thyrotropin is another name for TSH.

The hypothalamus releases TRH in response to low thyroid hormone levels.

The pituitary releases TSH in response to TRH.

The thyroid releases thyroid hormones in response to TSH.


Hi .. humanbean

TRH stimulation test , it will be a good idea to ask the doctor. I don'r know why he didn't consider the hypothalamus!

in ACTH challenge, we find that there is no deficiency in ACTH. As cortisol is just little bit above double after ACTH injection. meaning pituitary is producing enough ACTH. and less likely to have TRH deficiency. My doctor say that he seen before patients who have only low TSH while other hormones from pituitary were normal.


I'm not going to suggest a specific page in this link because I wouldn't know which one was relevant. But you might want to study it :

It's a link showing you all the tests that the endocrinology department ever does, and how they should be performed and interpreted. It is, as you will see, a little bit out of date, but still worth using as a reference.

There is another version of this which you might prefer - more up to date, but harder to read in my opinion :

1 like

You may also like...